1 .\" Copyright (c) 2003-2007 Tim Kientzle
2 .\" Copyright (c) 2017 Martin Matuska
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33 .Nd manipulate tape archives
36 .Op Ar bundled-flags Ao args Ac
37 .Op Ao Ar file Ac | Ao Ar pattern Ac ...
41 .Op Ar files | Ar directories
46 .Op Ar files | Ar directories
53 creates and manipulates streaming archive files.
54 This implementation can extract from tar, pax, cpio, zip, jar, ar, xar,
55 rpm, 7-zip, and ISO 9660 cdrom images and can create tar, pax, cpio, ar, zip,
56 7-zip, and shar archives.
58 The first synopsis form shows a
61 This usage is provided for compatibility with historical implementations.
62 See COMPATIBILITY below for details.
64 The other synopsis forms show the preferred usage.
67 is a mode indicator from the following list:
68 .Bl -tag -compact -width indent
70 Create a new archive containing the specified items.
71 The long option form is
76 but new entries are appended to the archive.
77 Note that this only works on uncompressed archives stored in regular files.
81 The long option form is
84 List archive contents to stdout.
85 The long option form is
90 but new entries are added only if they have a modification date
91 newer than the corresponding entry in the archive.
92 Note that this only works on uncompressed archives stored in regular files.
99 Extract to disk from the archive.
100 If a file with the same name appears more than once in the archive,
101 each copy will be extracted, with later copies overwriting (replacing)
103 The long option form is
112 mode, each specified file or directory is added to the
113 archive in the order specified on the command line.
114 By default, the contents of each directory are also archived.
116 In extract or list mode, the entire command line
117 is read and parsed before the archive is opened.
118 The pathnames or patterns on the command line indicate
119 which items in the archive should be processed.
120 Patterns are shell-style globbing patterns as
124 Unless specifically stated otherwise, options are applicable in
126 .Bl -tag -width indent
127 .It Cm @ Ns Pa archive
129 The specified archive is opened and the entries
130 in it will be appended to the current archive.
132 .Dl Nm Fl c Fl f Pa - Pa newfile Cm @ Ns Pa original.tar
133 writes a new archive to standard output containing a file
135 and all of the entries from
138 .Dl Nm Fl c Fl f Pa - Pa newfile Pa original.tar
139 creates a new archive with only two entries.
141 .Dl Nm Fl czf Pa - Fl Fl format Cm pax Cm @ Ns Pa -
142 reads an archive from standard input (whose format will be determined
143 automatically) and converts it into a gzip-compressed
144 pax-format archive on stdout.
147 can be used to convert archives from one format to another.
148 .It Fl a , Fl Fl auto-compress
150 Use the archive suffix to decide a set of the format and
153 .Dl Nm Fl a Fl cf Pa archive.tgz source.c source.h
154 creates a new archive with restricted pax format and gzip compression,
155 .Dl Nm Fl a Fl cf Pa archive.tar.bz2.uu source.c source.h
156 creates a new archive with restricted pax format and bzip2 compression
157 and uuencode compression,
158 .Dl Nm Fl a Fl cf Pa archive.zip source.c source.h
159 creates a new archive with zip format,
160 .Dl Nm Fl a Fl jcf Pa archive.tgz source.c source.h
163 option, and creates a new archive with restricted pax format
164 and gzip compression,
165 .Dl Nm Fl a Fl jcf Pa archive.xxx source.c source.h
166 if it is unknown suffix or no suffix, creates a new archive with
167 restricted pax format and bzip2 compression.
169 (c, r, u, x modes only)
170 Archive or extract POSIX.1e or NFSv4 ACLs. This is the reverse of
172 and the default behavior in c, r, and u modes (except on Mac OS X) or if
174 is run in x mode as root. On Mac OS X this option translates extended ACLs
175 to NFSv4 ACLs. To store extended ACLs the
178 .It Fl B , Fl Fl read-full-blocks
179 Ignored for compatibility with other
182 .It Fl b Ar blocksize , Fl Fl block-size Ar blocksize
183 Specify the block size, in 512-byte records, for tape drive I/O.
184 As a rule, this argument is only needed when reading from or writing
185 to tape drives, and usually not even then as the default block size of
186 20 records (10240 bytes) is very common.
187 .It Fl C Ar directory , Fl Fl cd Ar directory , Fl Fl directory Ar directory
188 In c and r mode, this changes the directory before adding
190 In x mode, change directories after opening the archive
191 but before extracting entries from the archive.
195 to the current directory after processing any
197 options and before extracting any files.
198 .It Fl Fl clear-nochange-fflags
200 Before removing file system objects to replace them, clear platform-specific
201 file flags that might prevent removal.
202 .It Fl Fl exclude Ar pattern
203 Do not process files or directories that match the
205 Note that exclusions take precedence over patterns or filenames
206 specified on the command line.
208 (c, r, u, x modes only)
209 Archive or extract file flags. This is the reverse of
211 and the default behavior in c, r, and u modes or if
213 is run in x mode as root.
214 .It Fl Fl format Ar format
216 Use the specified format for the created archive.
217 Supported formats include
223 Other formats may also be supported; see
224 .Xr libarchive-formats 5
225 for more information about currently-supported formats.
226 In r and u modes, when extending an existing archive, the format specified
227 here must be compatible with the format of the existing archive on disk.
228 .It Fl f Ar file , Fl Fl file Ar file
229 Read the archive from or write the archive to the specified file.
232 for standard input or standard output.
233 The default varies by system;
238 on Linux, the default is
241 Use the provided group id number.
242 On extract, this overrides the group id in the archive;
243 the group name in the archive will be ignored.
244 On create, this overrides the group id read from disk;
247 is not also specified, the group name will be set to
249 .It Fl Fl gname Ar name
250 Use the provided group name.
251 On extract, this overrides the group name in the archive;
252 if the provided group name does not exist on the system,
254 (from the archive or from the
257 will be used instead.
258 On create, this sets the group name that will be stored
260 the name will not be verified against the system group database.
263 Symbolic links named on the command line will be followed; the
264 target of the link will be archived, not the link itself.
274 .It Fl Fl hfsCompression
276 Mac OS X specific (v10.6 or later). Compress extracted regular files with HFS+
278 .It Fl Fl ignore-zeros
280 .Fl Fl options Cm read_concatenated_archives
281 for compatibility with GNU tar.
282 .It Fl Fl include Ar pattern
283 Process only files or directories that match the specified pattern.
284 Note that exclusions specified with
286 take precedence over inclusions.
287 If no inclusions are explicitly specified, all entries are processed by
291 option is especially useful when filtering archives.
292 For example, the command
293 .Dl Nm Fl c Fl f Pa new.tar Fl Fl include='*foo*' Cm @ Ns Pa old.tgz
294 creates a new archive
296 containing only the entries from
298 containing the string
302 Compress the resulting archive with
304 In extract or list modes, this option is ignored.
307 implementation recognizes XZ compression automatically when reading archives.
308 .It Fl j , Fl Fl bzip , Fl Fl bzip2 , Fl Fl bunzip2
310 Compress the resulting archive with
312 In extract or list modes, this option is ignored.
315 implementation recognizes bzip2 compression automatically when reading
317 .It Fl k , Fl Fl keep-old-files
319 Do not overwrite existing files.
320 In particular, if a file appears more than once in an archive,
321 later copies will not overwrite earlier copies.
322 .It Fl Fl keep-newer-files
324 Do not overwrite existing files that are newer than the
325 versions appearing in the archive being extracted.
326 .It Fl L , Fl Fl dereference
328 All symbolic links will be followed.
329 Normally, symbolic links are archived as such.
330 With this option, the target of the link will be archived instead.
331 .It Fl l , Fl Fl check-links
333 Issue a warning message unless all links to each file are archived.
336 Compress the resulting archive with
338 In extract or list modes, this option is ignored.
341 implementation recognizes lrzip compression automatically when reading
345 Compress the archive with lz4-compatible compression before writing it.
346 In extract or list modes, this option is ignored.
349 implementation recognizes lz4 compression automatically when reading archives.
352 Compress the archive with zstd-compatible compression before writing it.
353 In extract or list modes, this option is ignored.
356 implementation recognizes zstd compression automatically when reading archives.
358 (c mode only) Compress the resulting archive with the original LZMA algorithm.
359 In extract or list modes, this option is ignored.
360 Use of this option is discouraged and new archives should be created with
365 implementation recognizes LZMA compression automatically when reading archives.
368 Compress the resulting archive with
370 In extract or list modes, this option is ignored.
373 implementation recognizes LZO compression automatically when reading archives.
374 .It Fl m , Fl Fl modification-time
376 Do not extract modification time.
377 By default, the modification time is set to the time stored in the archive.
378 .It Fl Fl mac-metadata
379 (c, r, u and x mode only)
380 Mac OS X specific. Archive or extract extended ACLs and extended attributes
383 in AppleDouble format. This is the reverse of
384 .Fl Fl no-mac-metadata .
385 and the default behavior in c, r, and u modes or if
387 is run in x mode as root.
388 .It Fl n , Fl Fl norecurse , Fl Fl no-recursion
390 Do not recursively archive the contents of directories.
391 .It Fl Fl newer Ar date
393 Only include files and directories newer than the specified date.
394 This compares ctime entries.
395 .It Fl Fl newer-mtime Ar date
399 except it compares mtime entries instead of ctime entries.
400 .It Fl Fl newer-than Pa file
402 Only include files and directories newer than the specified file.
403 This compares ctime entries.
404 .It Fl Fl newer-mtime-than Pa file
408 except it compares mtime entries instead of ctime entries.
411 Honor the nodump file flag by skipping this file.
412 .It Fl Fl nopreserveHFSCompression
414 Mac OS X specific (v10.6 or later). Do not compress extracted regular files
415 which were compressed with HFS+ compression before archived.
416 By default, compress the regular files again with HFS+ compression.
422 Filenames or patterns are separated by null characters,
424 This is often used to read filenames output by the
429 (c, r, u, x modes only)
430 Do not archive or extract POSIX.1e or NFSv4 ACLs. This is the reverse of
432 and the default behavior if
434 is run as non-root in x mode (on Mac OS X as any user in c, r, u and x modes).
436 (c, r, u, x modes only)
437 Do not archive or extract file flags. This is the reverse of
439 and the default behavior if
441 is run as non-root in x mode.
442 .It Fl Fl no-mac-metadata
444 Mac OS X specific. Do not archive or extract ACLs and extended attributes using
446 in AppleDouble format. This is the reverse of
447 .Fl Fl mac-metadata .
448 and the default behavior if
450 is run as non-root in x mode.
451 .It Fl n , Fl Fl norecurse , Fl Fl no-recursion
452 .It Fl Fl no-same-owner
454 Do not extract owner and group IDs.
455 This is the reverse of
457 and the default behavior if
460 .It Fl Fl no-same-permissions
462 Do not extract full permissions (SGID, SUID, sticky bit, ACLs,
463 extended attributes or extended file flags).
464 This is the reverse of
466 and the default behavior if
470 (c, r, u, x modes only)
471 Do not archive or extract extended attributes. This is the reverse of
473 and the default behavior if
475 is run as non-root in x mode.
476 .It Fl Fl numeric-owner
477 This is equivalent to
482 On extract, it causes user and group names in the archive
483 to be ignored in favor of the numeric user and group ids.
484 On create, it causes user and group names to not be stored
486 .It Fl O , Fl Fl to-stdout
488 In extract (-x) mode, files will be written to standard out rather than
489 being extracted to disk.
490 In list (-t) mode, the file listing will be written to stderr rather than
494 Use the user and group of the user running the program rather
495 than those specified in the archive.
496 Note that this has no significance unless
498 is specified, and the program is being run by the root user.
499 In this case, the file modes and flags from
500 the archive will be restored, but ACLs or owner information in
501 the archive will be discarded.
505 .Fl Fl format Ar ustar
506 .It Fl Fl older Ar date
508 Only include files and directories older than the specified date.
509 This compares ctime entries.
510 .It Fl Fl older-mtime Ar date
514 except it compares mtime entries instead of ctime entries.
515 .It Fl Fl older-than Pa file
517 Only include files and directories older than the specified file.
518 This compares ctime entries.
519 .It Fl Fl older-mtime-than Pa file
523 except it compares mtime entries instead of ctime entries.
524 .It Fl Fl one-file-system
526 Do not cross mount points.
527 .It Fl Fl options Ar options
528 Select optional behaviors for particular modules.
529 The argument is a text string containing comma-separated
531 These are passed to the modules that handle particular
532 formats to control how those formats will behave.
533 Each option has one of the following forms:
534 .Bl -tag -compact -width indent
536 The key will be set to the specified value in every module that supports it.
537 Modules that do not support this key will ignore it.
539 The key will be enabled in every module that supports it.
540 This is equivalent to
543 The key will be disabled in every module that supports it.
544 .It Ar module:key=value , Ar module:key , Ar module:!key
545 As above, but the corresponding key and value will be provided
546 only to modules whose name matches
549 The currently supported modules and keys are:
550 .Bl -tag -compact -width indent
551 .It Cm iso9660:joliet
552 Support Joliet extensions.
553 This is enabled by default, use
558 .It Cm iso9660:rockridge
559 Support Rock Ridge extensions.
560 This is enabled by default, use
563 .Cm iso9660:!rockridge
565 .It Cm gzip:compression-level
566 A decimal integer from 1 to 9 specifying the gzip compression level.
567 .It Cm gzip:timestamp
568 Store timestamp. This is enabled by default, use
573 .It Cm lrzip:compression Ns = Ns Ar type
576 as compression method.
577 Supported values are bzip2, gzip, lzo (ultra fast),
578 and zpaq (best, extremely slow).
579 .It Cm lrzip:compression-level
580 A decimal integer from 1 to 9 specifying the lrzip compression level.
581 .It Cm lz4:compression-level
582 A decimal integer from 1 to 9 specifying the lzop compression level.
583 .It Cm lz4:stream-checksum
584 Enable stream checksum. This is by default, use
585 .Cm lz4:!stream-checksum
587 .It Cm lz4:block-checksum
588 Enable block checksum (Disabled by default).
589 .It Cm lz4:block-size
590 A decimal integer from 4 to 7 specifying the lz4 compression block size
591 (7 is set by default).
592 .It Cm lz4:block-dependence
593 Use the previous block of the block being compressed for
594 a compression dictionary to improve compression ratio.
595 .It Cm zstd:compression-level
596 A decimal integer from 1 to 22 specifying the zstd compression level.
597 .It Cm lzop:compression-level
598 A decimal integer from 1 to 9 specifying the lzop compression level.
599 .It Cm xz:compression-level
600 A decimal integer from 0 to 9 specifying the xz compression level.
601 .It Cm mtree: Ns Ar keyword
602 The mtree writer module allows you to specify which mtree keywords
603 will be included in the output.
604 Supported keywords include:
605 .Cm cksum , Cm device , Cm flags , Cm gid , Cm gname , Cm indent ,
606 .Cm link , Cm md5 , Cm mode , Cm nlink , Cm rmd160 , Cm sha1 , Cm sha256 ,
607 .Cm sha384 , Cm sha512 , Cm size , Cm time , Cm uid , Cm uname .
608 The default is equivalent to:
609 .Dq device, flags, gid, gname, link, mode, nlink, size, time, type, uid, uname .
611 Enables all of the above keywords.
614 to disable all keywords.
620 Produce human-readable output by indenting options and splitting lines
621 to fit into 80 columns.
622 .It Cm zip:compression Ns = Ns Ar type
625 as compression method.
626 Supported values are store (uncompressed) and deflate (gzip algorithm).
627 .It Cm zip:encryption
628 Enable encryption using traditional zip encryption.
629 .It Cm zip:encryption Ns = Ns Ar type
633 Supported values are zipcrypt (traditional zip encryption),
634 aes128 (WinZip AES-128 encryption) and aes256 (WinZip AES-256 encryption).
635 .It Cm read_concatenated_archives
636 Ignore zeroed blocks in the archive, which occurs when multiple tar archives
637 have been concatenated together. Without this option, only the contents of
638 the first concatenated archive would be read. This option is comparable to
640 .Fl i , Fl Fl ignore-zeros
643 If a provided option is not supported by any module, that
645 .It Fl P , Fl Fl absolute-paths
647 By default, absolute pathnames (those that begin with a /
648 character) have the leading slash removed both when creating archives
649 and extracting from them.
652 will refuse to extract archive entries whose pathnames contain
654 or whose target directory would be altered by a symlink.
655 This option suppresses these behaviors.
656 .It Fl p , Fl Fl insecure , Fl Fl preserve-permissions
658 Preserve file permissions.
659 Attempt to restore the full permissions, including owner, file modes, ACLs,
660 extended attributes and extended file flags, if available, for each item
661 extracted from the archive. This is te reverse of
662 .Fl Fl no-same-permissions
665 is being run by root and can be partially overridden by also specifying
668 .Fl Fl no-mac-metadata
671 .It Fl Fl passphrase Ar passphrase
674 is used to extract or create an encrypted archive.
675 Currently, zip is the only supported format that supports encryption.
676 You shouldn't use this option unless you realize how insecure
677 use of this option is.
682 .It Fl q , Fl Fl fast-read
684 Extract or list only the first archive entry that matches each pattern
686 Exit as soon as each specified pattern or filename has been matched.
687 By default, the archive is always read to the very end, since
688 there can be multiple entries with the same name and, by convention,
689 later entries overwrite earlier entries.
690 This option is provided as a performance optimization.
693 Extract files as sparse files.
694 For every block on disk, check first if it contains only NULL bytes and seek
696 This works similar to the conv=sparse option of dd.
698 Modify file or archive member names according to
700 The pattern has the format
701 .Ar /old/new/ Ns Op ghHprRsS
704 is a basic regular expression,
706 is the replacement string of the matched part,
707 and the optional trailing letters modify
708 how the replacement is handled.
711 is not matched, the pattern is skipped.
714 ~ is substituted with the match, \e1 to \e9 with the content of
715 the corresponding captured group.
716 The optional trailing g specifies that matching should continue
717 after the matched part and stop on the first unmatched pattern.
718 The optional trailing s specifies that the pattern applies to the value
720 The optional trailing p specifies that after a successful substitution
721 the original path name and the new path name should be printed to
723 Optional trailing H, R, or S characters suppress substitutions
724 for hardlink targets, regular filenames, or symlink targets,
726 Optional trailing h, r, or s characters enable substitutions
727 for hardlink targets, regular filenames, or symlink targets,
731 which applies substitutions to all names.
732 In particular, it is never necessary to specify h, r, or s.
735 Extract owner and group IDs.
736 This is the reverse of
738 and the default behavior if
741 .It Fl Fl strip-components Ar count
742 Remove the specified number of leading path elements.
743 Pathnames with fewer elements will be silently skipped.
744 Note that the pathname is edited after checking inclusion/exclusion patterns
745 but before security checks.
746 .It Fl T Ar filename , Fl Fl files-from Ar filename
749 will read the list of names to be extracted from
753 will read names to be archived from
757 on a line by itself will cause the current directory to be changed to
758 the directory specified on the following line.
759 Names are terminated by newlines unless
764 also disables the special handling of lines containing
766 Note: If you are generating lists of files using
768 you probably want to use
773 After archiving all files, print a summary to stderr.
774 .It Fl U , Fl Fl unlink , Fl Fl unlink-first
776 Unlink files before creating them.
777 This can be a minor performance optimization if most files
778 already exist, but can make things slower if most files
779 do not already exist.
780 This flag also causes
782 to remove intervening directory symlinks instead of
784 See the SECURITY section below for more details.
786 Use the provided user id number and ignore the user
787 name from the archive.
790 is not also specified, the user name will be set to
792 .It Fl Fl uname Ar name
793 Use the provided user name.
794 On extract, this overrides the user name in the archive;
795 if the provided user name does not exist on the system,
796 it will be ignored and the user id
797 (from the archive or from the
800 will be used instead.
801 On create, this sets the user name that will be stored
803 the name is not verified against the system user database.
804 .It Fl Fl use-compress-program Ar program
805 Pipe the input (in x or t mode) or the output (in c mode) through
807 instead of using the builtin compression support.
808 .It Fl v , Fl Fl verbose
809 Produce verbose output.
810 In create and extract modes,
812 will list each file name as it is read from or written to
816 will produce output similar to that of
820 option will also provide ls-like details in create and extract mode.
827 .It Fl w , Fl Fl confirmation , Fl Fl interactive
828 Ask for confirmation for every action.
829 .It Fl X Ar filename , Fl Fl exclude-from Ar filename
830 Read a list of exclusion patterns from the specified file.
833 for more information about the handling of exclusions.
835 (c, r, u, x modes only)
836 Archive or extract extended attributes. This is the reverse of
838 and the default behavior in c, r, and u modes or if
840 is run in x mode as root.
843 Compress the resulting archive with
845 In extract or list modes, this option is ignored.
848 implementation recognizes bzip2 compression automatically when reading
850 .It Fl Z , Fl Fl compress , Fl Fl uncompress
852 Compress the resulting archive with
854 In extract or list modes, this option is ignored.
857 implementation recognizes compress compression automatically when reading
859 .It Fl z , Fl Fl gunzip , Fl Fl gzip
861 Compress the resulting archive with
863 In extract or list modes, this option is ignored.
866 implementation recognizes gzip compression automatically when reading
870 The following environment variables affect the execution of
872 .Bl -tag -width ".Ev BLOCKSIZE"
873 .It Ev TAR_READER_OPTIONS
874 The default options for format readers and compression readers.
877 option overrides this.
878 .It Ev TAR_WRITER_OPTIONS
879 The default options for format writers and compression writers.
882 option overrides this.
887 for more information.
892 option overrides this.
893 Please see the description of the
895 option above for more details.
897 The timezone to use when displaying dates.
900 for more information.
905 The following creates a new archive
908 that contains two files
912 .Dl Nm Fl czf Pa file.tar.gz Pa source.c Pa source.h
914 To view a detailed table of contents for this
916 .Dl Nm Fl tvf Pa file.tar.gz
918 To extract all entries from the archive on
919 the default tape drive:
922 To examine the contents of an ISO 9660 cdrom image:
923 .Dl Nm Fl tf Pa image.iso
925 To move file hierarchies, invoke
928 .Dl Nm Fl cf Pa - Fl C Pa srcdir\ . | Nm Fl xpf Pa - Fl C Pa destdir
929 or more traditionally
930 .Dl cd srcdir \&; Nm Fl cf Pa -\ . | ( cd destdir \&; Nm Fl xpf Pa - )
932 In create mode, the list of files and directories to be archived
933 can also include directory change instructions of the form
935 and archive inclusions of the form
936 .Cm @ Ns Pa archive-file .
937 For example, the command line
938 .Dl Nm Fl c Fl f Pa new.tar Pa foo1 Cm @ Ns Pa old.tgz Cm -C Ns Pa /tmp Pa foo2
939 will create a new archive
944 from the current directory and add it to the output archive.
945 It will then read each entry from
947 and add those entries to the output archive.
948 Finally, it will switch to the
952 to the output archive.
956 format can be used to create an output archive with arbitrary ownership,
957 permissions, or names that differ from existing data on disk:
959 .Bd -literal -offset indent
962 usr/bin uid=0 gid=0 mode=0755 type=dir
963 usr/bin/ls uid=0 gid=0 mode=0755 type=file content=myls
964 $ tar -cvf output.tar @input.mtree
971 switches accept a variety of common date and time specifications, including
972 .Dq 12 Mar 2005 7:14:29pm ,
973 .Dq 2005-03-12 19:14 ,
976 .Dq 19:14 PST May 1 .
980 argument can be used to control various details of archive generation
982 For example, you can generate mtree output which only contains
987 .Dl Nm Fl cf Pa file.tar Fl Fl format=mtree Fl Fl options='!all,type,time,uid' Pa dir
988 or you can set the compression level used by gzip or xz compression:
989 .Dl Nm Fl czf Pa file.tar Fl Fl options='compression-level=9' .
990 For more details, see the explanation of the
991 .Fn archive_read_set_options
993 .Fn archive_write_set_options
994 API calls that are described in
997 .Xr archive_write 3 .
999 The bundled-arguments format is supported for compatibility
1000 with historic implementations.
1001 It consists of an initial word (with no leading - character) in which
1002 each character indicates an option.
1003 Arguments follow as separate words.
1004 The order of the arguments must match the order
1005 of the corresponding characters in the bundled command word.
1007 .Dl Nm Cm tbf 32 Pa file.tar
1008 specifies three flags
1017 flags both require arguments,
1018 so there must be two additional items
1019 on the command line.
1022 is the argument to the
1026 is the argument to the
1030 The mode options c, r, t, u, and x and the options
1031 b, f, l, m, o, v, and w comply with SUSv2.
1033 For maximum portability, scripts that invoke
1035 should use the bundled-argument format above, should limit
1050 Additional long options are provided to improve compatibility with other
1051 tar implementations.
1053 Certain security issues are common to many archiving programs, including
1055 In particular, carefully-crafted archives can request that
1057 extract files to locations outside of the target directory.
1058 This can potentially be used to cause unwitting users to overwrite
1059 files they did not intend to overwrite.
1060 If the archive is being extracted by the superuser, any file
1061 on the system can potentially be overwritten.
1062 There are three ways this can happen.
1065 has mechanisms to protect against each one,
1066 savvy users should be aware of the implications:
1067 .Bl -bullet -width indent
1069 Archive entries can have absolute pathnames.
1074 character from filenames before restoring them to guard against this problem.
1076 Archive entries can have pathnames that include
1081 will not extract files containing
1083 components in their pathname.
1085 Archive entries can exploit symbolic links to restore
1086 files to other directories.
1087 An archive can restore a symbolic link to another directory,
1088 then use that link to restore a file into that directory.
1089 To guard against this,
1091 checks each extracted path for symlinks.
1092 If the final path element is a symlink, it will be removed
1093 and replaced with the archive entry.
1096 is specified, any intermediate symlink will also be unconditionally removed.
1103 will refuse to extract the entry.
1105 To protect yourself, you should be wary of any archives that
1106 come from untrusted sources.
1107 You should examine the contents of an archive with
1108 .Dl Nm Fl tf Pa filename
1112 option to ensure that
1114 will not overwrite any existing files or the
1116 option to remove any pre-existing files.
1117 You should generally not extract archives while running with super-user
1123 disables the security checks above and allows you to extract
1124 an archive while preserving any absolute pathnames,
1126 components, or symlinks to other directories.
1137 .Xr libarchive-formats 5 ,
1140 There is no current POSIX standard for the tar command; it appeared
1143 but was dropped from
1145 The options supported by this implementation were developed by surveying a
1146 number of existing tar implementations as well as the old POSIX specification
1147 for tar and the current POSIX specification for pax.
1149 The ustar and pax interchange file formats are defined by
1151 for the pax command.
1155 command appeared in Seventh Edition Unix, which was released in January, 1979.
1156 There have been numerous other implementations,
1157 many of which extended the file format.
1160 public-domain implementation (circa November, 1987)
1161 was quite influential, and formed the basis of GNU tar.
1162 GNU tar was included as the standard system tar
1168 This is a complete re-implementation based on the
1171 It was first released with
1175 This program follows
1177 for the definition of the
1180 Note that GNU tar prior to version 1.15 treated
1182 as a synonym for the
1183 .Fl Fl one-file-system
1188 option may differ from historic implementations.
1190 All archive output is written in correctly-sized blocks, even
1191 if the output is being compressed.
1192 Whether or not the last output block is padded to a full
1193 block size varies depending on the format and the
1195 For tar and cpio formats, the last block of output is padded
1196 to a full block size if the output is being
1197 written to standard output or to a character or block device such as
1199 If the output is being written to a regular file, the last block
1201 Many compressors, including
1205 complain about the null padding when decompressing an archive created by
1207 although they still extract it correctly.
1209 The compression and decompression is implemented internally, so
1210 there may be insignificant differences between the compressed output
1212 .Dl Nm Fl czf Pa - file
1213 and that generated by
1214 .Dl Nm Fl cf Pa - file | Nm gzip
1216 The default should be to read and write archives to the standard I/O paths,
1217 but tradition (and POSIX) dictates otherwise.
1223 modes require that the archive be uncompressed
1224 and located in a regular file on disk.
1225 Other archives can be modified using
1231 To archive a file called
1235 you must specify it as
1241 In create mode, a leading
1246 is stripped unless the
1248 option is specified.
1250 There needs to be better support for file selection on both create
1253 There is not yet any support for multi-volume archives.
1255 Converting between dissimilar archive formats (such as tar and cpio) using the
1257 convention can cause hard link information to be lost.
1258 (This is a consequence of the incompatible ways that different archive
1259 formats store hardlink information.)